zig-chrono/src/timezone.zig

103 lines
2.7 KiB
Zig

const std = @import("std");
const debug = std.debug;
const testing = std.testing;
pub const TimeZoneTag = enum(u1) {
utc,
offset,
};
pub const Sign = enum(u1) {
positive,
negative,
};
const HoursMinutes = struct {
hours: u4,
minutes: ?u6,
};
pub const Offset = union(Sign) {
positive: HoursMinutes,
negative: HoursMinutes,
const Self = @This();
pub fn new(hours: i8, minutes: ?u6) ?Self {
if (hours > 12 or hours < -12) {
return null;
}
if (minutes) |m| {
if (m > 59) return null;
if (hours == 0 and m == 0) return null;
} else if (hours == 0) return null;
if (hours < 0) {
const h = @intCast(u4, @as(i8, hours) * -1);
return Self{ .negative = .{ .hours = h, .minutes = minutes } };
} else {
return Self{ .positive = .{ .hours = @intCast(u4, hours), .minutes = minutes } };
}
}
pub fn asSeconds(self: Self) i64 {
return switch (self) {
.positive => |ofs| blk: {
var seconds = @as(i64, ofs.hours) * 3600;
if (ofs.minutes) |m| seconds += (@as(i64, m) * 60);
break :blk seconds;
},
.negative => |ofs| blk: {
var seconds = @as(i64, ofs.hours) * 3600;
if (ofs.minutes) |m| seconds += (@as(i64, m) * 60);
break :blk seconds * -1;
},
};
}
};
pub const TimeZone = union(TimeZoneTag) {
utc: void,
offset: Offset,
const Self = @This();
pub fn new(hours: ?i8, minutes: ?u6) ?Self {
return if (hours) |h| blk: {
if (h == 0) {
break :blk .utc;
} else if (Offset.new(h, minutes)) |ofs| {
break :blk Self{ .offset = ofs };
} else {
break :blk null;
}
} else if (minutes) |m| Self{ .offset = Offset.new(0, m).? } else .utc;
}
pub fn format(
self: Self,
comptime fmt: []const u8,
options: std.fmt.FormatOptions,
writer: anytype,
) !void {
_ = fmt;
_ = options;
switch (self) {
.utc => try writer.writeAll("Z"),
.offset => |ofs| switch (ofs) {
.positive => |p| {
try writer.print("+{d:0>2}", .{p.hours});
if (p.minutes) |m| {
try writer.print(":{d:0>2}", .{m});
}
},
.negative => |n| {
try writer.print("-{d:0>2}", .{n.hours});
if (n.minutes) |m| {
try writer.print(":{d:0>2}", .{m});
}
},
},
}
}
};